Electroplating is a technique which involves applying a voltage between a substrate, such as a wafer, and an anode to form a metal film on a surface of the substrate. An electroplating apparatus for performing electroplating will be described with reference to FIG. 17. As shown in FIG. 17, the plating apparatus includes a plating tank 101 for holding a plating solution therein, an anode 102 disposed in the plating tank 101, an anode holder 103 for holding the anode 102, and a substrate holder 104 for holding a substrate W. The anode 102 and the substrate W are disposed such that they are opposite each other in the plating solution.
The plating apparatus further includes a regulation plate 106 for regulating the distribution of electric potential on the substrate W. The regulation plate 106 is disposed between the substrate W and the anode 102, and has an opening 106a which allows passage of an electric current that flows from the anode 102 to the substrate W.
The anode 102 is coupled via the anode holder 103 to the positive pole of a power source 107, while the substrate W is coupled via the substrate holder 104 to the negative pole of the power source 107. When a voltage is applied between the anode 102 and the substrate W, an electric current flows from the anode 102 to the substrate W through the opening 106a of the regulation plate 106, so that a metal film is formed on the surface of the substrate W.
In order to make the thickness of the metal film uniform, it is important to set the anode holder 103, the substrate holder 104 and the regulation plate 106 such that the anode 102, the substrate W and the regulation plate 106 are parallel to each other, and that the center of the anode 102, the center of the substrate W and the center of the opening 106a of the regulation plate 106 are aligned in a straight line. In view of this, a positioning holder 108 for holding upper portions of the anode holder 103, the substrate holder 104 and the regulation plate 106 may be provided above the plating tank 101.
However, the positioning holder 108 may deform due to the weights of the anode holder 103, the substrate holder 104 and the regulation plate 106. This may cause the anode 102, the substrate W and the regulation plate 106 to lean, and can therefore cause the center of the anode 102, the center of the substrate W and the center of the opening 106a of the regulation plate 106 to be out of alignment. With the recent demand for enhanced uniformity of a thickness of a metal film to be formed on the substrate W, there is a demand for more accurate positioning of the anode 102, the substrate W and the regulation plate 106.